review: unquote suite ID from url

[oliver-sanders]

• Closes https://github.com/cylc/cylc-flow/issues/5019
• Permit escape characters (e.g. "%2F" for "/") in suite IDs.

Requirements check-list

• [ ] I have read CONTRIBUTING.md and added my name as a Code Contributor.
• [ ] Contains logically grouped changes (else tidy your branch by rebase).
• [ ] Does not contain off-topic changes (use other PRs for other changes).
• [ ] Applied any dependency changes to both setup.cfg and conda-environment.yml.

• [ ] Appropriate tests are included (unit and/or functional).
• [ ] Already covered by existing tests.
• [ ] Does not need tests (why?).

• [ ] Appropriate change log entry included.
• [ ] No change log entry required (why? e.g. invisible to users).

• [ ] (master branch) I have opened a documentation PR at cylc/cylc-doc/pull/XXXX.
• [ ] (7.8.x branch) I have updated the documentation in this PR branch.
• [ ] No documentation update required.

[wxtim]

I had not been aware of urllib.unquote, but this is the sort of thing I'd have expected when I looked at this issue.

[oliver-sanders]

Nope, this wasn't it, replacing with https://github.com/cylc/cylc-flow/pull/5097